use crate::util::crc16;
use crc_catalog::Algorithm;
mod bytewise;
mod nolookup;
mod slice16;
const fn init(algorithm: &Algorithm<u16>, initial: u16) -> u16 {
if algorithm.refin {
initial.reverse_bits() >> (16u8 - algorithm.width)
} else {
initial << (16u8 - algorithm.width)
}
}
const fn finalize(algorithm: &Algorithm<u16>, mut crc: u16) -> u16 {
if algorithm.refin ^ algorithm.refout {
crc = crc.reverse_bits();
}
if !algorithm.refout {
crc >>= 16u8 - algorithm.width;
}
crc ^ algorithm.xorout
}
const fn update_nolookup(mut crc: u16, algorithm: &Algorithm<u16>, bytes: &[u8]) -> u16 {
let poly = if algorithm.refin {
let poly = algorithm.poly.reverse_bits();
poly >> (16u8 - algorithm.width)
} else {
algorithm.poly << (16u8 - algorithm.width)
};
let mut i = 0;
if algorithm.refin {
while i < bytes.len() {
let to_crc = (crc ^ bytes[i] as u16) & 0xFF;
crc = crc16(poly, algorithm.refin, to_crc) ^ (crc >> 8);
i += 1;
}
} else {
while i < bytes.len() {
let to_crc = ((crc >> 8) ^ bytes[i] as u16) & 0xFF;
crc = crc16(poly, algorithm.refin, to_crc) ^ (crc << 8);
i += 1;
}
}
crc
}
const fn update_bytewise(mut crc: u16, reflect: bool, table: &[u16; 256], bytes: &[u8]) -> u16 {
let mut i = 0;
if reflect {
while i < bytes.len() {
let table_index = ((crc ^ bytes[i] as u16) & 0xFF) as usize;
crc = table[table_index] ^ (crc >> 8);
i += 1;
}
} else {
while i < bytes.len() {
let table_index = (((crc >> 8) ^ bytes[i] as u16) & 0xFF) as usize;
crc = table[table_index] ^ (crc << 8);
i += 1;
}
}
crc
}
const fn update_slice16(
mut crc: u16,
reflect: bool,
table: &[[u16; 256]; 16],
bytes: &[u8],
) -> u16 {
let len = bytes.len();
let mut i = 0;
if reflect {
while i + 16 <= len {
let current0 = bytes[i] ^ (crc as u8);
let current1 = bytes[i + 1] ^ ((crc >> 8) as u8);
crc = table[0][bytes[i + 15] as usize]
^ table[1][bytes[i + 14] as usize]
^ table[2][bytes[i + 13] as usize]
^ table[3][bytes[i + 12] as usize]
^ table[4][bytes[i + 11] as usize]
^ table[5][bytes[i + 10] as usize]
^ table[6][bytes[i + 9] as usize]
^ table[7][bytes[i + 8] as usize]
^ table[8][bytes[i + 7] as usize]
^ table[9][bytes[i + 6] as usize]
^ table[10][bytes[i + 5] as usize]
^ table[11][bytes[i + 4] as usize]
^ table[12][bytes[i + 3] as usize]
^ table[13][bytes[i + 2] as usize]
^ table[14][current1 as usize]
^ table[15][current0 as usize];
i += 16;
}
while i < len {
let table_index = ((crc ^ bytes[i] as u16) & 0xFF) as usize;
crc = table[0][table_index] ^ (crc >> 8);
i += 1;
}
} else {
while i + 16 <= len {
let current0 = bytes[i] ^ ((crc >> 8) as u8);
let current1 = bytes[i + 1] ^ (crc as u8);
crc = table[0][bytes[i + 15] as usize]
^ table[1][bytes[i + 14] as usize]
^ table[2][bytes[i + 13] as usize]
^ table[3][bytes[i + 12] as usize]
^ table[4][bytes[i + 11] as usize]
^ table[5][bytes[i + 10] as usize]
^ table[6][bytes[i + 9] as usize]
^ table[7][bytes[i + 8] as usize]
^ table[8][bytes[i + 7] as usize]
^ table[9][bytes[i + 6] as usize]
^ table[10][bytes[i + 5] as usize]
^ table[11][bytes[i + 4] as usize]
^ table[12][bytes[i + 3] as usize]
^ table[13][bytes[i + 2] as usize]
^ table[14][current1 as usize]
^ table[15][current0 as usize];
i += 16;
}
while i < len {
let table_index = (((crc >> 8) ^ bytes[i] as u16) & 0xFF) as usize;
crc = table[0][table_index] ^ (crc << 8);
i += 1;
}
}
crc
}
#[cfg(test)]
mod test {
use crate::*;
use crc_catalog::{Algorithm, CRC_16_IBM_SDLC};
#[test]
fn correctness() {
let data: &[&str] = &[
"",
"1",
"1234",
"123456789",
"0123456789ABCDE",
"01234567890ABCDEFGHIJK",
"01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK01234567890ABCDEFGHIJK",
];
pub const CRC_16_IBM_SDLC_NONREFLEX: Algorithm<u16> = Algorithm {
width: 16,
poly: 0x1021,
init: 0xffff,
refin: false,
refout: true,
xorout: 0xffff,
check: 0x906e,
residue: 0xf0b8,
};
let algs_to_test = [&CRC_16_IBM_SDLC, &CRC_16_IBM_SDLC_NONREFLEX];
for alg in algs_to_test {
for data in data {
let crc_slice16 = Crc::<u16, Table<16>>::new(alg);
let crc_nolookup = Crc::<u16, NoTable>::new(alg);
let expected = Crc::<u16, Table<1>>::new(alg).checksum(data.as_bytes());
assert_eq!(crc_slice16.checksum(data.as_bytes()), expected);
assert_eq!(crc_nolookup.checksum(data.as_bytes()), expected);
let mut digest = crc_slice16.digest();
digest.update(data.as_bytes());
assert_eq!(digest.finalize(), expected);
let mut digest = crc_nolookup.digest();
digest.update(data.as_bytes());
assert_eq!(digest.finalize(), expected);
if data.len() > 2 {
let data = data.as_bytes();
let data1 = &data[..data.len() / 2];
let data2 = &data[data.len() / 2..];
let mut digest = crc_slice16.digest();
digest.update(data1);
digest.update(data2);
assert_eq!(digest.finalize(), expected);
let mut digest = crc_nolookup.digest();
digest.update(data1);
digest.update(data2);
assert_eq!(digest.finalize(), expected);
}
}
}
}
}